This study will advance several goals of the NIH Action Plan: 1) establish a multidisciplinary team to develop quantitative methodologies and imaging protocols for liver, 2) validate diagnostic criteria and methodologies for imaging in liver in both a cross-sectional and a longitudinal dietary intervention study of patients with NAFLD, 3) create a liver tissue bank with correlative imaging data, 4) develop reliable non-invasive MR markers to distinguish simple steatosis from NASH, and 5) define the dynamic changes in metabolism, energy homeostasis, and MR biomarkers as they relate to fructose-related liver injury.